Or you could turn your complaints into a song, as the Complaints Choir of Helsinki did (and Edinburgh, Toronto, Singapore — which was banned apparently, and Chicago, and yes, Tokyo, too. See a list on Wikipedia for all the other cities that have made Complaint Choirs.)

BTW, in Japanese, people use the word “claimer” to mean someone who complains. It’s a Japanglish word, or at least it’s not used that way in American English, so the person you’re talking to may not understand what you mean. You can use the word “claimant” but it’s legalese. I’d just say “someone who complains” or maybe a “complainer”, but even that word isn’t really used that much.